Fuel injector



y 1951 o. FRENCH 2,552,777

FUEL INJECTOR Filed Nov. 10, 1947 INVENTOR. a5 as t h 55 O, +MHOL Patented May 15, 1951 UNITED STATES PATENT OFFICE 7 Claims.

The invention relates to liquid fuel injectors for internal combustion engines and more particularly to automatic fuel injectors in which the pump and nozzle are associated as a unit.

One of the objects of the invention is to provide an automatic fuel injector in which the stroke of the high pressure fuel pump is variably limited by the variable metering of a checking liquid in a chamber associated with the outer end of the operating piston and in which the fuel supplied to the fuel pump is continuously circulated through the operating piston to cool the same and serve as a lubricant for the inner ring carrying portion of said operating piston.

A further object of the invention is to provide, in an automatic injector having a fixed spray pattern, a metering member forming part of the operating piston but angularly adjustable relative to the spray nozzle to control a hydraulic checking liquid to vary the stroke of the high pressure fuel pump, the adjustment of said mem her being through means at the outer end portion of the injector and forming a part of the variable volume chamber for said checking liquid.

A further object of the invention is to provide, in an injector of the type above described, an operating piston of light weight construction and thus reduce any effects that may be occasioned by the high speed operation of the injector particularly those occurring when the injector comes to rest at the ends of its inward and outward strokes.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a vertical sectional view through afuel injector embodying the invention;

Fig. 2 is a horizontal sectional view of the injector alone taken on the line 2-2 of Fig. 1;

Fig. 3 is an elevation view of the operating piston;

Fig. 4 is an elevation view of the metering control member;

Fig. 5 is a vertical sectional view through the operating piston showing certain modifications;

Fig. 6 is a diagrammatic view of an injector installation. 1

Referring to the drawings, the injector has the relatively fixed metal housing parts comprising a piston stop 8, cylinder 9, cap I0, and nut I I.

Stop 8 is a ring seating on an annular flange l2 formed in the head I3 of an internal combustion engine and having a valve seat surface I4.

The cylinder 9 has a preferably straight bore I5, 2. fuel inlet passage I6 connected with said bore by a port IT, a relief port I8, a shoulder or seat I9 at the outer end of the bore l5, and a threaded bore 29. For a fixed spray pattern, a threaded opening 2| for a key 22 is provided.

The cap I0 fits loosely in the bore 20, so that it may be shifted relative to its seat to center parts hereinafter described and is clamped in fluid-tight engagement with the seat I9 by a sleeve nut II engaging the bore 20. This cap has an inlet 23 for a cushioning liquid, preferably a lubricant, a conical bore 24 connected with a guide bore 25, a fuel outlet 26, and a threaded enlargement 21 at the outer end of the bore 25.

The above described housing is adapted to be clamped in assembled relation in the head l3 with the end of the cylinder 9 abutting the stop 8 by any suitable form of clamp (not shown).

Referring to Figs. 1 to 4 of the drawings, a fluid pressure operated piston working in the cylinder 9 comprises an operating piston 28 and a checking piston 29. The operating piston 28, made up of one or more parts, is formed to provide a fuel pump barrel 30, a ring carrying part 3|, a valve housing 32, and an annular cooling space 33 between the parts 3! and 32. It may be formed as a one piece casting of suitable alloy steel, or it may be formed as shown of two sleeve parts, brazed or welded together, one of these parts including the barrel 30 and housing 32 and the other the part 3I in which instance the first mentioned sleeve part may be of alloy steel and the part 3| of cast iron, aluminum alloy, or magnesium alloy provided with grooves to receive the piston sealing means, such as the rings 34. The housing part 32 has a head portion 35 which is provided with a conical valve surface 36 of less diameter than the bore I5 to seat on the seat I4 to initially reduce the area exposed to the com pressed gases in the engine cylinder and permit of rapid acceleration of the piston after leaving its seat. The housing 32 has a bore 3'! joining the barrel 30 at a shoulder 38 and having its other end threaded 39 to receive a nozzle clamp ing sleeve nut 40, and it has a key slotted extension M in which thekey 22 works.

The checking piston 29 may be of one or more pieces but preferably is formed of two metal sleeves 42 and 43 having a drive or press fit connection with each other, so that these sleeves can each be finished to fit other cooperative parts before they are united together. The sleeve 42 is differentially bored as shown, and its outer end is recessed to provide a V-shaped notch 44 providing control edges 45 and 46 cooperat- 3 ing with the relief port 58 to control the stroke of the piston and hence the amount of fuel delivered to the engine. The sleeve 33 has an inwardly extending flange ll seating on a part of the barrel 3i} and provided with diametrically disposed key slots 48 and passages 3.

The valving and spray nozzle mounted in the housing 32 may be of a suitable construction, and as an example I have shown an apertured valve disk or seat 49, clamped against the shoulder 38 by a nozzle member 53 which is engaged the sleeve nut all. A fuel control discharge valve is normally seated against the seat 69 by a spring 52 interposed between the head of'said valve and a seat in a bore 53 of the member 553 which bore connects by a valve guide bore 84 with the spray orifices 55, the stem of the valve being flatted to permit fuel passage through bore 54.

A high pressure fuel plunger 56 works in the barrel andcontrols the fuel inlet ports 5? in said barrel which are supplied with fuel from the space 53 between pistons 23 and 29.

For angularly adjusting the piston 29, a metering control member 59, having a valved headfill seating on the seat 2-% and a shank '6! rotatably mounted in the bore 25, has a cylindrical extension 62 provided withdiametrically disposed key projections '63 slidably engaging the key slots 48 whereby rotation of member '59 rotates the piston 29. The inner end of the head'efi projects beyond the extension 52 to form a differential pressure 'area 64 to aid in holding said head in fluid-tightengagement with its seat on an'increase inpressure in the checking fluid chamber formed between the cylinder 9, cap I0, piston 29,and extension 52. To permit passage of fuel from the outer end of "the bore 15 to the outlet 26 the head of the plunger 55 has a diametrically disposed groove 68 alined with a bore 61 in member 59 which connects with a cross bore '61 communicating with an annular groove 68 in the shank 6| alined with said outlet. A stuffing box 69 mounted in the bore 21 engages the shank 6! whose exposed outer end carries a crank arm 16 that may be oscillated manuall or through suitable governor control.

The outer end of the plunger 56 has a selfcentering abutting engagement with thehead 69 which due to the self-centering connection of thecap Ill with thecylinder is also self-centering relative to the inner bore or wall of the piston 29 which slidably engages the extension 62, and as the piston 29 has its flange Ll! spaced from the barrel 3Q, it is also self -centering in the bore 15 and independently of the part 3! of the operating piston. The self-centering of the above parts is of importance insecuring good fits between the relatively slidably movable parts above described, and it also permits, if necessary, of an increase in diameter of that portion of the bore in cylinder 9 in which the piston 25% works to provide such a cross-sectional area to said piston working in'the checking chamber as to reduce the magnitude of the'pressure in the chamber 65 and thus guard against leakage losses of the checking flund where the pressures in chamber 65 would be excessive if a straight bore H. were used. Thus while a straight bore [5.11s preferred, there may be instances in practice where this bore is formed of differential bores when the outer diameter of the piston 29 is greater than that of the part 3! of the operating piston for the reasons above mentioned.

A piston return spring H is interposed between the flange ll of piston 29' and the head of ill plunger 56 and acts to hold said plunger against longitudinal movement, head 66 against cap i0, piston 29 in abutting engagement with piston 28 and the conical surface 36 against seat Hi.

Referring to Fig. 6, fuel is continuously circulated through the injector in any of its operating positions while the engine is running from a supply tank i2 connected by a pipe 13 with a low pressure pump 14 connected by a pipe 75, associated with a cooler 16, with the inlet l6 which connects with the lower end of the bore it through the port i'i delivering fuel to the space 58 at the inner end of the piston which is its hottest operating part, the fuel then flowing upwardly through the passages 43 to the outer end of the cylinder 9, thence through the groove fiii'intheheadof the plunger to the passages 61, 61, and 68 and outlet 2% to a pipe ll leading back to the tank 72, the pipe also being equipped with the usual strainers (not-shown). Thusthe fuel passing through the space 58:sup plies the high pressure fuel pump with its charge, cools'the piston and also lubricates thewallsof the bore iii: in which theoperating piston works.

The chamber 65 maybe supplied with a checking fluid, preferably ailubricant, from a tank 1-8 that may have a supply connection with thereli'ef port l8 where the spring'll alone'is used to control the time of the beginning of injection, but wherea variable timing of injection is desiredto suitvarying compressi'on'pressures that may occur in the engine, the 'tank '18 connects bya pipe'lQ with the inlet 23 through a suitable spring closed valve'fitting'fifl, andthe relief port ithas a suitable spring closed needle relief valve fitting 8! connected bya return ipe 32 with'the tank, 'thetension of the spring of said relief valve being adjustable to vary the time of in-.

jection by varying the pressure inthe chamber 2 65 necessary to open said valve and start the movement of the operating piston. The valves til and '8! may be ofany suitable construction, reference being made to my'copending application Serial No. 592,675, filed May 8, 1945, now Patent 'No. 2,516,690, dated July 25,1950, for a detailed showingof these valves. The tank T8 has been shown arranged for gravity feed, but any suitable low pressure pump may be associated with said tank, if desired, to supply checking fluid to the chamber '65. Should any seepage from the chamber 65 to'the space 58 occur such seepage will be incorporated in the'fuel and become a part of the fuel charge.

With the above construction, when the compression pressure of the engine is sufficient to overcome the loading of the spring ll alone or the loading of the valve 86, whenused, the-piston structure above described is moved outwardly, its movement being accelerated as it moves off its seat I l, and when during this movement the plunger 56 laps the ports 5'l, fuel'is'compressed in the barrel 3!) until its pressure is sufficient to overcome the tension of the spring'52 and lift the discharge valve 5| off its seat to allow fuel to flow through thespray orifices 55 into the combustion chamber C of the engine. When this outward movement of the piston reaches a point where the control edge 45 laps the relief port [8, the lubricant or liquid in the chamber'55 will act as a hydraulic stop to arrest further movement of said piston, and depending upon the angular setting of the piston 29 by the adjustment control member 59 will depend the extent of outward movement or stroke of said piston structure and hence the amount of fuel deli'vered'to'the engine by the .high pressure fuel pump; On the release of. pressure in the engine cylinder, the, spring ll returns the piston parts to their initial position.

When a fixed spray pattern is not desired as where a centrally located nozzle discharges in a symmetrically formed combustion chamber so that possible rotary shifting of the fuel jet or jets will not change the combustion characteristics, then the key 22 and the slotted extension-4| of the piston 28 may be omitted and the sleeve nut d8 dispensed with by a direct threaded connection of the nozzle member 56 with thread 39, or if further simplification of the piston structure is desired, it may be formed as shown in Fig. 5 wherein the piston 29 may be integral withthe parts 3-H and 32 of the operating piston and made of cast iron, or a suitable aluminum or magnesium alloy, and the high pressure pump barrel of suitable alloy steel is a separate part mounted in the differential bores 83 and 84 and clamped in position by the nozzle member 85 which has a direct threaded connection with the thread 86 of the bore 85, the member 85 also having the valve surface 36' formed thereon corresponding in function to the surface 36 of the first described construction. In this form the flange 81 connects the piston 29 directly with the operating piston, and the keys 63 work in arcuate lots 83, similar to the slots 48 shown in Fig. 2, this piston having the same mode of operation as the first described form except that its parts turn as a unit.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in the claims.

What I claim as my invention is:

1. In an automatic fuel injector, the combination of a housing having a cylinder bore, a reciprocatory piston working in said bore in response to gases under compression, said piston having a high pressure fuel pump chamber, a pump plunger working in said chamber and held against longitudinal movement, a variable by draulic stop means between said housing and the outer end of said piston to vary the stroke of said piston, said bore and said piston forming a cooling chamber extending to the inner end of said piston and separate from said stop means and. operatively connected with said housing, and means for circulating fuel through said cooling chamber.

2. In an automatic fuel injector, the combination of a housing having a cylinder bore provided with a relief port, a reciprocatory piston working in said bore in response to gases under compression having an actuating piston portion, and a checking piston portion provided with a control edge angularly shiftable relative to said relief port, said actuating piston portion having a high pressure fuel pump chamber, a pump plunger working in said chamber and held against longitudinal movement, a variable volume checking fluid chamber at the outer end of said piston comprising said housing, said checking piston and a metering control member for angularly shifting said checking piston portion relative to said relief port to vary the volume of said chamber, said metering control member being operable from outside said housing and having a valved head seating on the outer end of said housing having a differential pressure area exposed to the fluid in said checking fluid chamber, and means for supplying fuel to said fuel pump chamber.

3. In an automatic fuel injector, the combination of. a housing having a cylinder bore, a reciprocatory piston structure working in said bore in response to gases under compression comprising an actuating piston and a checking piston movable angularly relative to said actuating piston, said actuating piston having a high pressure fuel pump chamber, a pump plunger working in said chamber and held against longitudinal movement, a variable volume checking fluid chamber at the outer end of said piston comprising said housing, said checking piston and a metering control member for angularly adjusting said checking piston, said housing having a relief port and said checking piston having a control edge cooperating with said relief port to vary the volume of said chamber, and means for supplying fuel to said fuel pump chamber.

4. In an automatic fuel injector, the combination of a housing having a cylinder bore. a reciprocatory piston structure working in said bore in response to gases under compression comprising an actuating piston and checking piston having an inwardly extending flange rotatably mounted on a part of said actuating piston and provided with keyways, said actuating piston having a high pressure fuel pump chamber, a pump plunger working in said chamber and held against longitudinal movement, a variable volume checking fluid chamber at the outer end of said piston comprising said housing, said checking piston and a metering control member provided with keys engaging said keyways for angulariy adjusting said checking piston, said housing having a relief port and said checking piston having a control edge cooperating with said relief port to vary the volume of said chamber. and means for supplying fuel to said pump chamber.

5. In an automatic fuel injector, the combination of a housing, a reciprocatory piston structure working in said housing in response to gases under compression comprising an actuating piston and a checking piston, said actuating piston having a high pressure fuel pump chamber, a pump plunger working in said chamber and held against longidutinal movement, a variable volume checking fluid chamber at the outer end of said piston structure comprising said housing, said checking piston and a metering control member provided with key projections, said checking piston comprising inner and outer sleeve members, said inner sleeve having a flanged portion rotatably mounted on a part of said actuating piston and provided with keyways engaging said key projections for angularly adjusting said checking piston, said housing having a relief port communicating with said checking fluid chamber and said checking piston having a control edge cooperating with said relief port to vary the volume of said chamber, and means for supplying fuel to said pump chamber.

6. In an automatic fuel injector, the combination of a housing having a bore and a cap at one end of said bore, a piston structure working in said bore in response to gases under compression comprising an actuating piston and a checking piston mounted for angular movement relative to said actuating piston and having a self-centering engagement with said bore and provided with a bore, an actuator rotatably mounted in said cap and having a cylindrical extension working in the bore in said checking piston and a keyed connection with said piston for angularly adjusting the same, said cap having amounting in said housing permitting self-centering of said actuator relative to said checking piston, said actuating. piston having a high pressure pump chamber, a pump plunger working in said pump chamber, a spring interposed between said plunger and said piston structure for holding said. plunger against longitudinal movement in self-centering contact with said actuator and for returning said piston, said housing having a rel-iei. port and said checking piston having a control edge cooperating with said relief port to vary the stroke of said piston structure, and means for supplying fuel to said fuel pump chamber.

7. In an automatic fuel injector as claimed in cl'aimr'l wherein the piston includes a checking piston and an operating piston connected i70 f gether by a flange slotted to provide keyways and the hydraulic stop means includes a member provided with keys engaging in said keyways.

LOUIS O. FRENCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

